JPS60193152A - Motor controller of vtr - Google Patents

Abstract

PURPOSE:To perform accurate and speedy still picture reproduction, and to improve the operability, simplify the constitution, and to reduce the cost by sectioning phase relation into specific areas and storing corresponding motor control information in the areas, judging which area the phase relation corresponds to during variable speed reproduction, and driving a motor for driving a recording medium. CONSTITUTION:A still picture command signal S12 from a key matrix circuit 37 falls to a low level at the time of a change from a normal reproduction mode to a still reproduction mode, and still picture processing is performed. Then, the common terminal (c) of switch circuits 42 and 43 is switched from a normally close terminal (b) to a normally open terminal (a). Then, a capstan computer 31 is switched from the state wherein it is controlled by a normal capstan servo part 44 to the state wherein it is controlled with a drive output signal S13 and a run-direction output signal S14 outputted by the output circuit 41 of a microcomputer 31.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor control device for a VTR, and particularly to a VTR motor control device suitable for use in variable speed playback such as steel playback.
This invention relates to a motor control device for a TR.

BACKGROUND TECHNOLOGY AND PROBLEMS When performing still playback on a home-type VTR, for example, the running of the video tape is stopped and the drum on which the video head is mounted is normally rotated for playback. In that case, the trunk in which one field's worth of image information is recorded and the trajectory of the video head will inevitably not be parallel to each other as shown in Figure 1, and the trajectory of the head indicated by the broken line in the same figure will be closer to the track. The tape is inclined at an angle closer to the tape running direction than the Tr.

Usually a 3-head V with an auxiliary head for variable speed playback.
In the TR, as shown in FIG. 2, one main head HA and the other main head HB are provided with a predetermined minute gap (an electrical gap of 1:25H, for example, 556 μm).
) is located close to the auxiliary head for variable speed playback (
When the head azimuth angle is between the head azimuth angle of the head HA and the head azimuth angle (Head azimuth angle), playback is performed by alternately scanning one track with Hc. I don't get it. The portion where trunks with different azimuths are scanned becomes noise on the screen. Therefore, it is necessary to make sure that the noise appears during the blanking period, and never to appear at least near the center of the screen in the vertical direction.Therefore, the trajectory of the head must intersect with the trunk at approximately the center of the screen. The head must be scanned so that the Therefore, the positional relationship between the tape track and the head is a factor that determines whether variable speed playback can be performed satisfactorily.
In order to perform good variable speed playback, the tape must be stopped so that its trunk is in the above-mentioned positional relationship with the head.

Fig. 3 shows an example of a conventional VTR motor control device configured with a so-called discrete circuit. -(2A) input terminal to which the reproduction signal of is supplied.

(2B) is a preamplifier that amplifies the reproduced signal from the input terminal (LA) and (IB>, (3) is a preamplifier (2A)
.

(2B) is a switch circuit for switching the output; (4) is a pulse generator that is provided in the drum motor (not shown) and generates a signal of one pulse every time the drum motor rotates once; The signal from the generator (4) indicates the rotational phase of the head and its frequency is 30Hz. (
5) is an RF switching signal generation circuit that outputs an RF switching signal based on the signal output from the pulse generator (4), and this RF switching signal is used as a switching signal for the switch circuit (3). (6) is a dropout compensation circuit that compensates for dropouts in the reproduced signal output from the switch circuit (3); (7) is a limiter that removes level fluctuations in the reproduced signal; (8)
is an FM demodulator that performs FM demodulation of the reproduced signal, and (9) is an output terminal, and the demodulated signal obtained at this output terminal (9) is processed by a de-emphasis circuit, a bypass filter, etc. (not shown). output via

Qll is a step pulse generation circuit which, when an RF switching signal is supplied, generates a step pulse having a frequency that is one-fourth of the frequency of the RF switching signal, and the step pulse outputted from this step pulse generation circuit αψ. The pulses are supplied to the capstan motor drive circuit (12) via a sealed sui-nona circuit (11). (13) is a waveform shaping circuit that generates a noise position signal having a certain phase difference with the RF switching signal when it is supplied, and (14) a phase that compares the phase of the noise position signal with a noise pulse to be described later. A comparator,
The output signal of this phase comparator (14) is supplied to the SW7000 circuit (11) as a switching signal and is used as the first switching signal for head He and head VHc.

The noise pulse whose phase is compared with the noise position signal in the phase comparator (14) is passed through the dropout compensation circuit (
The noise detection signal detected by the dropout detection circuit (not shown) in 6) is waveform-shaped by a waveform shaping circuit (15). That is, the dropout compensation circuit (6) reproduces a signal from one horizontal period before when a dropout occurs in the reproduced signal, and the dropout detection circuit (6) detects noise occurring during horizontal scanning. Therefore, this dropout detection circuit can detect °ζ noise, and the noise pulse, which is the output of this dropout detection circuit, and the above-mentioned noise position signal. It is possible to detect the position on the screen where the noise hand occurs (position in the river surface direction) by comparing the phase of The phases of the waveform-shaped noise pulse and the noise position signal are compared.

The phase comparator (14) outputs a high level output signal when both the noise position signal and the noise pulse are at high level, and is in the open state. J1 (11) is opened, and the step pulse from the step pulse intervention circuit α0 is activated to drive the carburetor tongue motor drive circuit II (12).
prevent it from being supplied to Also, head HB and head H
As described above, the head switching between the two and the third and fourth positions is also performed.

(16) is a normal/variable speed playback switching circuit for switching between normal playback and variable speed playback, which plays back the control signal recorded on the control track of the tape, and also outputs a signal obtained by waveform shaping. It is always supplied, and when a still playback operation is performed, a pause signal is supplied from the system control computer. When the pause signal is supplied, a servo switching signal is sent to the capstan motor drive 19 (12) with a predetermined time delay from the control signal. This servo switching signal is a signal for servo switching between normal playback and variable speed playback. (17) is a brake pulse generation circuit that sends a brake pulse signal to the capstan motor drive circuit (12) in response to the above-mentioned servo switching signal. M is a capstan motor.

Next, the operation of the circuit shown in FIG. 3 will be explained with reference to FIG. 4.

During normal reproduction, the switch circuit (11) is kept closed, while the RF switching signal generating circuit (5) synchronizes with the output signal S1 as shown in FIG. 4A from the pulse generator (4). An RF switching signal S2 as shown in FIG. 4B is generated.

Then, this signal S2 is frequency-divided by 1/4 by the step pulse generation circuit Ol, and 4tt of step pulses P1 as shown in FIG. 4C are supplied to the capstan motor drive circuit (12). Therefore, during normal playback, the capstan motor drive circuit (12) continues to drive the motor M under the control of the step pulse, and the tape runs at the normal running speed.

When a still playback operation is performed, a pause signal Sf as shown in FIG.
, is supplied (1).Then, the normal/shift repartitioning circuit (I6) outputs the fourth signal after inputting the pause signal S6.
After a certain time delay from the rising edge of the first pulse of the control signal S5 as shown in Figure G, the servo J converter No. 4F1 S7 as shown in Figure 4 I is supplied to the capstan motor drive-11R (12). At the same time, it is supplied to the brake pulse generation circuit (17). When the brake pulse generation circuit (17) receives the servo switching signal S7, it supplies a brake pulse P3 as shown in FIG. 4J to the capstan motor drive circuit (12). 12) causes the motor M to stop.

The generation timing and pulse width of this brake pulse P3 are set and adjusted so that the tape can be stopped almost just before the optimal position for still playback. Therefore, by the functions of the normal/variable speed playback switching circuit (16) and the brake pulse generation circuit (17), the tape is decelerated to a substantially stopped state near the optimal position for steel playback.

When the tape is decelerated in this way, a noise pulse P2 is output from the dropout compensation circuit (6) and shaped by the waveform shaping circuit (15) as shown in FIG.
The phase of the noise position signal S3 gradually changes to match the phase of the noise position signal S3 from the waveform shaping circuit (13) as shown in the fourth diagram. This is because the noise position signal S
In 2.3, the phase is set and adjusted so that it occurs at the same timing as the noise pulse P2 that occurs when the optimum conditions for still playback are established. When the tape is decelerated and approaches the optimal position for still playback, the
Naturally, the phase of the nozzle pulse P2 is equal to the noise position signal S.
It approaches the phase of 3. Then, when the phases match, the signal is transferred from the phase comparator (14) to the switch circuit (11) in Fig. 4F.
A switching signal as shown in is supplied, and the switch circuit (11
) is in the open state as shown by the two-dot chain line in Figure 3. Then, the transmission of the step pulse P1 to the capstan motor drive circuit (2) is blocked by the switch circuit (11), and the tape stops at a substantially optimal position on the steel circuit. At the same time, a switch is made from a state in which iIt playback is performed by head H to a state in which playback is performed by video head 2 (A and IIC), that is, a head is switched, and still playback is performed.

As described above, capstan motors have conventionally been controlled using discrete circuits, but this requires a large number of parts, increases the board area of the circuit, and increases costs. In addition, there are many adjustments that must be made extremely accurately, such as the phase difference between the control signal and the servo switching signal when a pause signal is input, and the pulse width of this servo switching signal, which increases the time required for adjustment. Furthermore, if the characteristics of the motor or other component parts change over time, this will lead to the same result as poor adjustment, making it impossible to regenerate the steel properly.

Purpose of the Invention The present invention has been made in view of the above points, and it is possible to accurately and quickly stop a videotape at an optimal still playback position without noise, regardless of variations in motor characteristics during variable speed playback. The present invention provides a motor control device for a VTR which has a small number of adjustment points and parts, and is inexpensive to manufacture.

Summary of the Invention In this invention, the phase of a switching signal for switching a plurality of magnetic heads alternately scanning tracks on a recording medium and a noise pulse generated when the magnetic head scans across a plurality of tracks is determined. a detection means for detecting a relationship;
Motor control information corresponding to each of these areas is stored in advance.
ζ determines which of the above regions the phase relationship corresponds to during variable speed playback, and stores data in the judgment region from the time the motor is stopped until the phase relationship reaches a value corresponding to the steel region. Based on the corresponding motor control information゛ζ
The apparatus is configured to include a driving means for driving the motor for driving the recording medium.

With such a configuration, accurate and rapid steel regeneration, improved workability, simplified configuration, and lower cost can be achieved.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on FIGS. 5 to 12.

Figure 5 shows the circuit configuration of this embodiment in its original form. In the figure, (218) (21B) are human power terminals, (22^) (2
2B) is a preamplifier, (23) is a switch circuit, (24
)4;! A pulse generator, (25) an RF switching signal generation circuit, (26) a dropout compensation circuit, (2
7) is a limiter, (28) is an FM demodulator, (29) is an output terminal, and (30) is a waveform shaping circuit.

In addition, these (l^) and (IB) to (30) are the third
They are used for the same purpose as (IA), (111) to (9) and (15) in the figure, and detailed explanation thereof will be omitted.

Reference numeral (31) is a system control microcomputer provided inside the VTR, which performs various controls on the VTR including control of the capstan motor M. (
32) is a CPU, (33) is a ROM, and this RO
The M (33) stores programs and basic data executed by the CPU (32), as well as a partial area (34
) stores the table. This table shows the noise pulse waveform shaped by the waveform shaping circuit (3o) and the R
R output from the F switching signal generation circuit (25)
Data that specifies the pulse width of the drive output signal and running direction output signal (torque direction output signal), which will be described later, corresponding to the phase difference between the F switching signal and the F switching signal. It stores information corresponding to the braking time calculated by d1 from the motor constant, motor drive main river, etc., and when it receives the address signal corresponding to the above phase difference, it outputs the drive output signal and running direction output corresponding to the phase difference. Outputs data specifying the pulse width of the signal. In addition, as will be described later, this table also shows that the phase between the noise pulse and the RF switching pulse is divided into several groups, and these groups are further divided into several regions, and each of these divided regions is divided into several groups. A fixed value for the area is stored as motor control data. (35) is a RAM, (36) is an input circuit to which the above-mentioned noise pulses and RF switching signals are supplied, and this input circuit (36) includes a power supply switch and other various input circuits. Signals from sensors, remote controllers, etc. are also supplied.

(37) is a keyma I/wax circuit provided outside the microcomputer (31), (38) is a key decoder that decodes the key signal from the toma link circuit (37), and (39) is a RAM (35). (40) is a timer in another area of the same RAM ('35), (41) is a drive output signal,
This is an output circuit that outputs various signals including a running direction output signal, a normal steel switching signal, and a head switching signal.

(42) and (43) are normal steel switching switch circuits, both of which are switched by the above-mentioned normal steel switching signal from the microcomputer (31).

The switch circuit (42) has a drive output signal from the microcomputer (31) supplied to its normally open switching terminal a, and a drive output signal from the normal capstan servo unit (44) to its closed switching terminal a. A drive output signal is sent from the common terminal C to the capstan motor drive circuit (45). On the other hand, the switch circuit (43
) has a microcomputer (3
1), a voltage E is supplied to its normally closed switching terminal, and a running direction output signal is sent from its common terminal C to the capstan motor drive circuit (45).

The normal capstan servo section (44) is for running the tape in the normal direction at the normal speed.
a control signal played back from a videotape (47) as a recording medium by a control head (46);
A signal from the pulse generator (24) and a signal from the frequency generator (4B) of the motor M are supplied to the capstan motor so as to run the tape (47) at normal speed in synchronization with the reproduced control signal. Drive circuit (4
5) Control. In addition, the capstan motor drive circuit (4
5) When the drive output signal and the running direction output signal are supplied, the capstan motor M is rotated in the direction according to the content of the running direction output when the drive output is at a high level, and when the drive output signal is at a low level. 1@j so as to stop motor M. When the running direction output signal is at a high level, the tape is run in the normal playback direction, and when it is at a low level, the tape is run in the opposite direction.

Further, in the present invention, in order to quickly feed the tape to the steel line, the phase of the noise pulse with the RF switching pulse is divided into a plurality of groups and further into a plurality of regions as shown in FIG.

In other words, the phase that the noise pulse makes with the RF signal is divided into a plurality of regions, for example 1511111, one of which is defined as the steel region As corresponding to the steel line, and the remaining one excluding this steel region As.
The four areas a1 to a14 are divided into a plurality of groups, for example, three groups 01 to G3, and for example, group G1 is divided into areas a1 to a14.
a3, group G2 includes areas a4 to aB and group G3
includes areas a9 to a14.

FIG. 7 shows areas a1 to a14 and A divided in this way.
This shows an example of a specific method of allocating s to one period of RF switching signals.
represents one cycle (3011z) of the RF switching signal S11 from the RF switching signal generation circuit (25), and FIG.
-1"L" of the noise pulse P11 (see Fig. 12) obtained at the output side of the waveform shaping circuit (30) from the rising edge of the switching signal Szl = -1"L" = time from the rising edge of the RF switch No. Sll and noise pulse P
The force 1 sin 1~ value corresponding to the phase difference of 11 is expressed in time 'r, and the maximum is 33.3 m5-ffl.

In addition, Fig. 7C shows the rotation angle of the motor M corresponding to one cycle of the RF switching signal S +4, that is, the rotation angle θ of the motor M required to feed the tape to the thread line. It is assumed that one period force is <24°.

The seventh diagram represents the phase difference φ between the RF switching signal SsI and the noise pulse Pi1. For example, if a noise pulse P1'l is generated at jjλ at the rising edge of the cue RF switching fM signal S1t, the phase difference φ is 0°, RF
When the noise pulse PL'1 is generated at the rising edge of the switching signal Ss's, it becomes π (180''), and in the same manner as in 1, between CO and 2π, the noise pulse P L'1 becomes π (180'').
It can take any value depending on the point in time when 4 occurs. Also, the seventh
Figure E shows the divisions of groups 61 to G3 and the steel area As, and Figure 7F shows the respective groups.

Areas k14at to a3 falling in Gl, G2 and G3. a
4 to aS & a9 to a14 and a still area As, the position of this still area As is preferably located near the center of the latter half period of the RF switching signal Snt. Then, as described later, this steel area A
The optimal steel line is when the noise pulse arrives at approximately the center of s, and at this time the reproduction output of the head HB is at its minimum, and conversely, the reproduction output of the head HC, which is used in conjunction with this, is at its maximum.

Also, as can be seen from Fig. 7, the area a of each group
1 to a14 are set so that the range becomes wider as the steel area As gets closer to each group, and the noise pulse is set to move from one area of each group to near the center of the next group. Ru. In other words,
When the noise pulse enters a certain phase φ with respect to the RF switching signal S1'1, a step feed pulse is sent to the motor M so that the phase enters the next group. ) and a running direction output signal 314 (FIG. 12D). Then, when the phase φ enters a certain region of a certain group, a step feed pulse is given to the motor M so that the noise pulse enters the next group.

The time or pulse width of the acceleration pulse (drive output signal) and brake pulse (travel direction output signal) after this step feed pulse corresponds to each area kg a1 to a14, respectively, so that the phase of the noise pulse is This is a fixed value determined to move approximately to the center of the group, and this value is stored in advance as data in the table (34) of the ROM (33).

Note that the movement of this noise pulse, that is, the acceleration time and shake-half time for rotating the motor M by an angle θ, can be calculated if the constant of the motor M, the driving voltage of the motor M, and the value of the negative front torque are known. It can be easily attached.

However, if the acceleration time and braking time are fixed values, then the average of the motor constants (A is the fixed value, so due to variations in the motor constants, etc.) The phase shift p of the noise pulse with respect to RF switching (g+;'i-) also varies, and as a result, the destination of the noise pulse when step-feeding varies around the center of the next group.

FIG. 8 shows an example of a movement destination range expanded due to variations in the group range and motor constants, etc. For example, from the range rin of area n of the i-th group, the next 1+1
When moving the noise pulse to the second group, if there are no variations in motor constants, etc., the destination range is the range shown by rt in the figure, which is approximately the same range as the range rtn before movement. However, if the amount of movement is slow due to variations in the motor constants, etc., it will change as shown by the symbol a, and conversely, if the amount of movement is insufficient due to variations, the symbol will already change. As a result, the movement destination range r2, which has been expanded due to variations in motor constants, etc., is always the range.

Therefore, in the present invention, the range r++L of the next i+1th group is determined to be large enough to at least cover the movement destination range r2 expanded by this variation. As a result, even if the destination of the noise pulse due to step feeding expands due to variations in motor constants, etc., it will not go outside the range of the group.

Next, the operation of the circuit shown in FIG. 5 will be explained with reference to FIGS. 9 to 12.

Now, when the main power of the VTR is turned on, the program starts as shown in Figure 9, and the key matrix circuit (
37), it is determined in step (51) whether or not the operation command was manually issued. If the operation command is not manually input, the determination is repeated until the operation command is manually input.

When the manual operation command is input, it is determined in step (52) whether the content of the manual operation command is a command to switch from the normal reproduction mode to the steel reproduction mode.

In the case of switching from the normal reproduction mode to the steal replay mode, the steal 1it order signal S12 from the key matrix circuit (37) goes from the low level to the high level in accordance with No. 12111B, and as shown in FIG. A still process indicating f-thinness is performed in step (53). When this steal processing is completed, the human power of the operation command is 'I'l
Returning to the first step (51) of determining

Next, if the switching is not from the normal playback mode to the still playback mode, it is determined in step (54) whether the content of the input operation command is a command to switch from the still playback mode to the normal playback mode. It will be held in

In the case of switching from the still playback mode to the normal playback mode, in other words, the still command signal S1 is not shown in FIG. 12B.
2 changes from the high level to the low level, a switching process from the still playback mode to the normal playback mode, detailed in FIG. 11, is performed in step (55). When this process is finished, the process returns to the first step (51).

If the switching is not from the still playback mode to the normal playback mode, the steal processing in step (53) and the switching process from the steel 411 raw mode to the normal playback mode in step (55) are excluded for <V'l'H. General control takes place in step (56).

When this general control is completed, the process returns to the first step (51).

Next, steel processing will be explained in more detail according to No. 101g+.

In the case of switching from normal playback mode to still playback mode, when switching from normal playback mode to still playback mode,
That is, processing for switching various signals from the normal reproduction mode to the stealth and 714 re-habitation modes is performed in step (57). Through this process, the normal steel switching signal S16 from the output circuit (41) is switched from high level to low level, as shown in FIG. 12E. Then, the switches liJ MA (42) and (43) switch from the state where the common terminal C is connected to the sealed terminal A to the state where it is connected to the 1π open terminal A, and as a result, the capstan motor M is switched to the normal state. Controlled by the drive output signal S13 and running direction output signal 314 as shown in FIG. 12C and D, respectively, output by the output circuit (41) of the microcomputer (31) from the state controlled by the capstan servo unit <44xL. The state changes to the state in which the

Then, in step C1 (58), the capstan motor M, which is rotating at the normal speed and direction, is abruptly stopped (in order to do so, the drive output signal S13 is switched from low level to high level, and the running direction output signal is switched from low level to high level). S14 is switched from a high level to a low level to generate torque in the reverse direction in the capstan motor M, and the capstan motor M is abruptly stopped. When the capstan motor M is completely stopped, the drive output signal S13 is set to high. At the same time, the running direction output signal S14 is switched from low level to high level to keep the capstan motor M in a stopped state.
As shown in FIG. 2, time Tb is the time during which the capstan motor M is braked.

When the capstan motor M comes to a stopped state, the process waits for a while in step (59).

Next, in step (60), a counter (28) is started to count the number of pulses of the drive output signal 313. The count of the number of pulses of the drive output No. 18 S13 is the count of the number of pulses of the drive output signal S13 generated until the noise pulse P1t as shown in FIG. 12F is generated from the waveform shaping circuit (30). . In this way, the number of pulses of the drive output signal 313 is counted. Even after the drive output signal S13 has stopped and the set number of pulses has arrived C, if the noise pulse P L'1 has not yet occurred, the noise pulse P L'1 is counted. This is to allow the program to proceed without waiting for its arrival. That is, in the process of transitioning from normal playback mode to steel playback mode, a noise pulse P1'l is normally generated, and that noise pulse P'
l'l and the RF switching signal s1 as shown in FIG. 12A from the RF switching signal generation circuit (25). After detecting the phase relationship between It is quite possible that the pulse P1'1 may not occur, or that a noise pulse P1'x may occur and C will not be able to detect it. If it occurs, noise pulse P 1'1
Program progress stops at the step where it waits for
As a result, the control function of the microcomputer (31) for the VTR may stop. Therefore, even if the number of pulses of the steel command manual labor live output signal S13 reaches a certain number, for example, 10 pulses (normally 2 to 5
Noise pulses occur at a pulse level. ) If the noise pulse P11 does not occur, the noise pulse P1'1
This allows forcibly switching the head and performing other processing necessary for the still playback mode without waiting for the occurrence of the error.

Note that the pulses of this drive output signal S13 are measured by a counter (
The step (60) of cents 39) only starts the counter (39) in the car, and the count amplifier is done in a step a little later.

Next, it is determined in step (61) whether the RF switching signal S l'l has fallen, and if it has fallen,
If not, this determination is repeated until it falls.

After the timer (40) is cleared in step (62) and time measurement is started, it is determined in step (63) whether or not the noise pulse PI has risen.

When the noise pulse P 1'x rises, step ((i
In step 4), time measurement by the timer (40) is stopped.

The time measured by the timer (40), the step (
65). This time 'r indicates the phase difference between the RF switching signal So and the noise pulse P1'l.

RF switching signal S l' when the time T measured by the timer (40) is optimal for still playback
The time difference Ts between the rising edge of l and the noise pulse P11
In step (6), it is determined whether or not the noise pulse P11 is equal to
Perform step 6).

The measurement time T of the timer (40) is the desired time difference TS mentioned above.
If it is equal to the tape (
Since head 47) can be said to be in an apparatus suitable for still playback, switching from head H, to r]c and other processes necessary for still playback are performed.

If the secondary time T of the timer (40) is not equal to the time difference 'rs, that is, the phase relationship between the RF switching signal S1'1 and the noise pulse Px'x is optimal for still reproduction. If not, in steps (68) to (70), the measurement time T and each area a1 to
A comparison with times T1 to Ti4 corresponding to a14 is performed sequentially.

In other words, first step (68) odor ζ, measurement time T
It is determined whether or not is equal to the time 1'1 corresponding to the area a1, and if they are equal, in step (71), the pulse width of the drive output signal S13 and the running direction output signal S14 is determined according to the time T I corresponding to the area a1. is read from the table (34).

-111 hours] is not equal to the time T1, it is determined in step (69) whether it is equal to the time T2 corresponding to the area a2, and if they are equal, the time T2 corresponding to the area a2 is determined in step (72). The pulse widths of the drive output signal 313 and the running direction output signal S14 corresponding to the output signal S14 are read out from the table (34).

Thereafter, the same judgment is made for the other regions a3 to axa, and the measurement time T and each region a3 to a'lJ are determined in the same manner.
If the times Ti to T13 corresponding to are equal, each area a3
The pulse widths of the drive output signal 313 and the traveling direction output signal S14 corresponding to times T3 to 'F13 corresponding to ~a13 are read out from the table (34), and if they are not equal, the pulse widths are sequentially moved to the next area. And step (
70), the measurement time 1゛ is the time T corresponding to the area a14.
14 and if they are equal, in step (73), the pulse width of the drive output signal 313 and the traveling direction output signal 314 corresponding to the time T1 corresponding to the area a14 is calculated from the table (34) as described above. When read, if they are not equal, it is determined that there is an abnormality (1) and all modes are stopped in step (74).

On the other hand, in step (63) the noise pulse P 1'
If 1 has not risen yet, RF switch leg signal S
Step (
75), and if it does not stand still, the noise pulse P
The process returns to step (63) in which it is determined whether or not 11 has risen.

If the RF switching signal Sl'l is rising (this means that one cycle of the RF switching signal S1t has elapsed since the rising of the RF switching signal Ssl detected in step (61)). ), in step (76), it is assumed that the noise pulse P l'l has risen and hit, and the drive output signal So pulse width and running direction output signal 314
The data specifying the minimum pulse width among the data specifying the pulse width of is not read from the table (34) of the ROM (33).

When step (73) or step (76) is completed, in step (77), the counter (39) for counting drive output pulses is amplified to l' I J count.

The reason for this counting is as described in the explanation of step (60) above.

Step (7) determines whether the count value of the counter (39) has reached a preset count value, e.g.
8), and if so, perform the step (67) described above.
processing and enters still playback.

The count value of the counter (39) reaches [“10”°ζ
If not, in step (79), the ROM (33)
RF according to the data read from the table (34).
Switching signal S1'l and noise pulse Pr's
drive output signal S with a pulse width corresponding to the phase relationship with
13, and further sends out a running direction output signal S14 with a pulse width corresponding to the pulse width. FIG. 12 shows the constant time Ts'r, which includes the drive output signal S13 and the traveling direction output signal S1.
4 represents the period during which the motor M is fed in steps, and when the signals 313 and S14 are both at high level, it is an acceleration time, and when the signal S13 is at a high level and the signal S14 is at a low level, it is a braking time. The rising timing of the running direction output signal 314 from low level to high level is made to coincide with the rising timing of the drive output signal S13 from low level to high level, and the F retiming, so that the timing of rising from the low level to the high level of the drive output signal S13 coincides with the F retiming. Intermittent feeding of a certain amount can be achieved by multiplying the

Incidentally, the time ``1'' between the rising edge of the RF switching signal S l'l and the rising edge of the noise pulse pH is 1.
Pulse width of culm drive output No. 313 smaller than ゛s (
However, the pulse width of this drive output signal 313 has a wide period of time during which the high level state continues (N), and the pulse width of the driving direction output signal 314 (this driving direction output signal St3 & Noculus IIti in Kotsumu 1- refers to the time when the low level is maintained. ) is also wide). The closer the time T is to 1゛5, the more the dry horn comes out (signal Sxi
and the width of the travel direction output signal 314 becomes narrower.

This means that the larger the position of the tape (47) deviates from the optimal position for Steel Playback G3, the larger the feed amount in the 11tl step feed will be. Optimal 43'1. This is to reduce the amount of travel in one run by /h as the distance approaches iW, so that positioning can be performed at a higher viscosity.

Next, regarding the switching process from the steel recut mode to the normal regeneration mode in step (55) of FIG.
This will be explained according to Figure 1.

When the steal release command is manually issued from the key matrix circuit (37), the steal command signal Sz2 becomes lower than the low level as shown in FIG. 12B, and after this level changes, the RF switch (No. The judgment of whether or not it has fallen is Ste Nof.

(80). If the RF switching signal S sl does not fall, the determination is repeated until it falls.

If the RF switching signal S1s is raised, then in step (81) ζ, time is measured by the timer (40). To measure this time, switch from still playback mode to normal playback mode in synchronization with RF Suinoching No. 1i S 1'l to avoid noise when switching from still playback mode to normal playback mode. Do this in order to be able to do so.

It is determined in step (82) whether the time 1' measured by the timer (40) exceeds a predetermined time TA. As this time T6, the RF loop notching signal S
The time required to reach the most favorable state for switching from the steel reproducing mode to the normal reproducing mode after the fall of 1'l is selected.

If the C1 measurement time T exceeds the predetermined time 'r6, then in step 83) the steel playback mode is switched to the normal playback mode. Includes St5 switching,
This signal 315 is shown in FIG.
T 6t & Switches from low level to high level. In addition, an output circuit for switching from head HC to HB (
41) as shown in Fig. 12G.
, 6 from high level to low level is also included.

However, this head switching is performed by RF after inputting the steal release command.
This is performed in synchronization with the next rising edge of the switching signal Ss'x.

In this way, in this embodiment, even if the rotation angle of the motor during step feeding varies due to variations in the motor constants, etc., the movement start is adjusted so that the motor stops in the area corresponding to the desired rotation angle. Set the size of the area and the size of the group to be moved to a range where the latter can sufficiently cover the former, and use a large step when the deviation is large from the optimal steel area, and a small step when the deviation is small. Since the motor is driven, it is possible to bring the motor to a standstill in the target area in a relatively short time even if the motor is driven with an acceleration time and braking time that match the average value of the 72' Eve constant. The optimum steel playback position can be obtained accurately and quickly.

Furthermore, if there is a deviation that causes the optimum steel regeneration position to go too far, it can be returned to the optimum steel regeneration position by rotating the motor M in the reverse direction.

Furthermore, as long as the data specifying the pulse width of the drive output signal with respect to the phase relationship between the RF switching signal and the noise pulse is appropriate, good still playback can be expected, and the hexacircle circle becomes unnecessary.

Furthermore, since a microcomputer is used to form the motor drive signal given to the cab scan drive circuit, the motor control signal should be formed using a system control microcomputer that controls the entire video tape recorder. I can do it. In addition, the head' position is detected by detecting the phase of the RF switching signal, and noise is detected by the dropout detection circuit built into the dropout compensation circuit, so a special circuit is required just for still playback. There is no need to set it up.

Note that so-called stop-motion playback can be performed by continuing this still playback, and slow-motion playback can be performed by alternating still playback and normal playback. Further, in the above-mentioned Φ embodiment, there are three groups, but the present invention is not limited to this. For example, group G2 may be omitted and there may be two groups, ζ, group G1 and group G3.

Modification Example In the above embodiment, °ζ is a drive output signal corresponding to the phase relationship between the todo switching signal and the noise pulse, and the pulse width of the running direction output signal is read from the table (34) of the ROM (33). However, instead of reading out the pulse width from the table (34), it is also possible to process the phase relationship according to a predetermined calculation formula and calculate the corresponding pulse width of the drive output signal, etc. be.

Effects of the Invention 1 As described above, according to the present invention, the phase relationship between the switching signal for switching the head and the noise pulse generated during variable speed playback is divided into a plurality of regions, and the motor control corresponding to each region is performed. Since information is given to the motor and the tape is gradually fed to the steel area, even if there are variations in the constants of the motor, this is effectively absorbed and accurate and rapid steel playback is possible.

In addition, since the capstan motor is controlled using a micro combinator, the microcomputer for VTR control can be used to control Cabsukun Tanabata.
There is no need to provide a special circuit for capstan motor control for steel regeneration. Therefore, it is possible to simplify the configuration and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the videotape trunk and the trajectory of the video head, Fig. 2 is a head arrangement of a 3-head system, Fig. ls3 is a block diagram of an example of a conventional oil production system, and Fig. 4 The figure is a waveform diagram for explaining the operation of Figure 3, Figure 5 is a neo block diagram of an embodiment of the present invention, and Figures 6 to 8 are
The figures are diagrams for explaining the present invention, FIG. 9 is a flowchart showing an outline of the microcomputer, and FIG.
FIG. 11 is a flowchart showing a specific program for steal processing, FIG. 11 is a flowchart showing a specific program for switching from steal to playback processing, and FIG. 12 is a waveform diagram showing various signals. (24) is a pulse generator, (25) is an RF switching signal generation circuit, (26) is a dropout compensation circuit, (
30) is a waveform shaping circuit, (31) is a microcomputer, (45) is a capstan motor drive unit, HA, HB
, HC is a video head, and M is a capstan motor. Figure 1 Figure 2 Figure 6 As

Claims (1)

[Claims] detection means for detecting a phase relationship between a switching signal for switching a plurality of magnetic heads alternately scanning tracks on a recording medium and a noise pulse generated when the magnetic head scans across the plurality of tracks; , a storage means that divides the phase relationship into a plurality of predetermined regions and stores in advance motor control information corresponding to each of the regions;
During variable speed playback, it is determined which of the above regions the phase relationship corresponds to, and the motor control information according to the judgment region is used from the time the motor is stopped until the phase relationship reaches a value corresponding to the steel region. and a drive means for driving the motor for driving the recording medium based on the temperature of the recording medium.